1. Field of the Invention
The present invention relates to an exchange apparatus which encloses a plurality of extension apparatuses and connects an extension terminal which was designated to extend from a line wire to the line wire.
2. Related Background Art
Hitherto, in a telephone exchange apparatus which can be connected to a digital network such as an ISDN or the like having the function to transmit attribute information of a transmission side terminal to a reception side terminal, when a call was received by a data terminal connected to the extension, if the attributes of the transmission side terminal and the reception side terminal differ, communication matching between the transmission and reception terminals cannot be obtained. Therefore, the telephone exchange apparatus executes a process to transmit a release completion message to the transmission side terminal or the like.
In the above example, the "attribute" indicates the information which needs to obtain the matching upon communication. For instance, in the ISDN, the "attribute" denotes the information which needs to obtain the matching upon communication such as synchronous/asynchronous data, the transmission rate, telephone/G3, and the like which are included in high order layer matching information elements, low order layer matching information element, and the like.
Therefore, in a telephone exchange apparatus which can be connected to a digital network such as an ISDN or the like having the function to transmit attribute information of a transmission side terminal to a reception side terminal, when a call is received by a data terminal connected to an extension, if the attributes such as data transmission rates or the like of the transmission side terminal and the reception side terminal differ, there occur inconveniences such that the call is disconnected, the communication cannot be started, and the like.
The above problems will now be described hereinbelow with reference to the drawings.
FIG. 6 is a flowchart showing the operation of a telephone exchange apparatus in the case where a call was transmitted from an ISDN and received by a data terminal connected to an extension of a conventional telephone exchange apparatus.
The conventional telephone exchange apparatus in the above case operates in the following manner.
That is, in the diagram, a check is made to see if a call has been received or not in step S601. If YES and when a call set message has been received from the network, an ISDN interface in the telephone exchange apparatus checks the content of a received subaddress information element in the call set message (step S602). Practically speaking, the presence or absence of the subaddress for the extension data terminal is discriminated. Thus, if the subaddress shown in the received subaddress information element differs from the subaddress of the data terminal connected to the extension, a receiving process such that an appointed extension is rung or the like is executed (step S603). On the other hand, if the subaddress exists and those subaddresses coincide (Step S602), the processing routine advances to step S604.
That is, if the subaddress shown in the received subaddress information element coincides with the subaddress of the data terminal connected to the extension telephone, step S604 follows. In step S604, a check is made to see if the high order layer matching information element and low order layer matching information element (attributes) of the transmission side terminal coincide with the high order layer matching information element and low order layer matching information element of the extension data terminal designated by the subaddress or not.
If the attributes of the transmission side terminal and the reception side terminal coincide as a result of the discrimination in step S604, step S605 follows. In step S605, a check is made to see if a transmission faculty information element of a call set message indicates a 3.1 kHz audio signal or an unlimited digital signal. A predetermined response process is executed in accordance with the result of the discrimination, thereby setting a communicable state. That is, if the transmission faculty information element indicates the 3.1 kHz audio signal, a response process I corresponding to it is executed (step S606). On the other hand, if it indicates the unlimited digital signal, a response process II corresponding to it is performed (step S607). Then, the program is finished.
On the other hand, in step S604, if the attributes such as data transmission rates or the like of the transmission side terminal and the reception side terminal, that is, the attributes between the transmission side terminal and the extension data terminal in this case differ, step S608 follows and the program is finished. That is, if the attributes of the transmission side terminal and the reception side terminal differ as a result of the discrimination in step S604, a release completion message is sent to the network.
As mentioned above, in the conventional apparatus, if the call was received by the data terminal connected to the extension, when the attributes of the transmission side terminal and the reception side terminal differ, the process to send the release completion message to the transmission side terminal or the like is executed. Therefore, the call is disconnected and there are the drawbacks that 1) in order to perform communication, it is necessary to change the setting after confirming the attribute of the partner side terminal and to newly start the communication process, and that 2) the operating efficiency is poor.